Let's get this math done. We have 643 and we're going to multiply it by 425. This is the same as taking 643 and adding it to itself 425 times.
Step 1: 0 + 643 = 643
Step 2: 643 + 643 = 1286
Step 3: 1286 + 643 = 1929
Step 4: 1929 + 643 = 2572
Step 5: 2572 + 643 = 3215
Step 6: 3215 + 643 = 3858
Step 7: 3858 + 643 = 4501
Step 8: 4501 + 643 = 5144
Step 9: 5144 + 643 = 5787
Step 10: 5787 + 643 = 6430
Step 11: 6430 + 643 = 7073
Step 12: 7073 + 643 = 7716
Step 13: 7716 + 643 = 8359
Step 14: 8359 + 643 = 9002
Step 15: 9002 + 643 = 9645
Step 16: 9645 + 643 = 10288
Step 17: 10288 + 643 = 10931
Step 18: 10931 + 643 = 11574
Step 19: 11574 + 643 = 12217
Step 20: 12217 + 643 = 12860
Step 21: 12860 + 643 = 13503
Step 22: 13503 + 643 = 14146
Step 23: 14146 + 643 = 14789
Step 24: 14789 + 643 = 15432
Step 25: 15432 + 643 = 16075
Step 26: 16075 + 643 = 16718
Step 27: 16718 + 643 = 17361
Step 28: 17361 + 643 = 18004
Step 29: 18004 + 643 = 18647
Step 30: 18647 + 643 = 19290
Step 31: 19290 + 643 = 19933
Step 32: 19933 + 643 = 20576
Step 33: 20576 + 643 = 21219
Step 34: 21219 + 643 = 21862
Step 35: 21862 + 643 = 22505
Step 36: 22505 + 643 = 23148
Step 37: 23148 + 643 = 23791
Step 38: 23791 + 643 = 24434
Step 39: 24434 + 643 = 25077
Step 40: 25077 + 643 = 25720
Step 41: 25720 + 643 = 26363
Step 42: 26363 + 643 = 27006
Step 43: 27006 + 643 = 27649
Step 44: 27649 + 643 = 28292
Step 45: 28292 + 643 = 28935
Step 46: 28935 + 643 = 29578
Step 47: 29578 + 643 = 30221
Step 48: 30221 + 643 = 30864
Step 49: 30864 + 643 = 31507
Step 50: 31507 + 643 = 32150
Step 51: 32150 + 643 = 32793
Step 52: 32793 + 643 = 33436
Step 53: 33436 + 643 = 34079
Step 54: 34079 + 643 = 34722
Step 55: 34722 + 643 = 35365
Step 56: 35365 + 643 = 36008
Step 57: 36008 + 643 = 36651
Step 58: 36651 + 643 = 37294
Step 59: 37294 + 643 = 37937
Step 60: 37937 + 643 = 38580
Step 61: 38580 + 643 = 39223
Step 62: 39223 + 643 = 39866
Step 63: 39866 + 643 = 40509
Step 64: 40509 + 643 = 41152
Step 65: 41152 + 643 = 41795
Step 66: 41795 + 643 = 42438
Step 67: 42438 + 643 = 43081
Step 68: 43081 + 643 = 43724
Step 69: 43724 + 643 = 44367
Step 70: 44367 + 643 = 45010
Step 71: 45010 + 643 = 45653
Step 72: 45653 + 643 = 46296
Step 73: 46296 + 643 = 46939
Step 74: 46939 + 643 = 47582
Step 75: 47582 + 643 = 48225
Step 76: 48225 + 643 = 48868
Step 77: 48868 + 643 = 49511
Step 78: 49511 + 643 = 50154
Step 79: 50154 + 643 = 50797
Step 80: 50797 + 643 = 51440
Step 81: 51440 + 643 = 52083
Step 82: 52083 + 643 = 52726
Step 83: 52726 + 643 = 53369
Step 84: 53369 + 643 = 54012
Step 85: 54012 + 643 = 54655
Step 86: 54655 + 643 = 55298
Step 87: 55298 + 643 = 55941
Step 88: 55941 + 643 = 56584
Step 89: 56584 + 643 = 57227
Step 90: 57227 + 643 = 57870
Step 91: 57870 + 643 = 58513
Step 92: 58513 + 643 = 59156
Step 93: 59156 + 643 = 59799
Step 94: 59799 + 643 = 60442
Step 95: 60442 + 643 = 61085
Step 96: 61085 + 643 = 61728
Step 97: 61728 + 643 = 62371
Step 98: 62371 + 643 = 63014
Step 99: 63014 + 643 = 63657
Step 100: 63657 + 643 = 64300
Step 101: 64300 + 643 = 64943
Step 102: 64943 + 643 = 65586
Step 103: 65586 + 643 = 66229
Step 104: 66229 + 643 = 66872
Step 105: 66872 + 643 = 67515
Step 106: 67515 + 643 = 68158
Step 107: 68158 + 643 = 68801
Step 108: 68801 + 643 = 69444
Step 109: 69444 + 643 = 70087
Step 110: 70087 + 643 = 70730
Step 111: 70730 + 643 = 71373
Step 112: 71373 + 643 = 72016
Step 113: 72016 + 643 = 72659
Step 114: 72659 + 643 = 73302
Step 115: 73302 + 643 = 73945
Step 116: 73945 + 643 = 74588
Step 117: 74588 + 643 = 75231
Step 118: 75231 + 643 = 75874
Step 119: 75874 + 643 = 76517
Step 120: 76517 + 643 = 77160
Step 121: 77160 + 643 = 77803
Step 122: 77803 + 643 = 78446
Step 123: 78446 + 643 = 79089
Step 124: 79089 + 643 = 79732
Step 125: 79732 + 643 = 80375
Step 126: 80375 + 643 = 81018
Step 127: 81018 + 643 = 81661
Step 128: 81661 + 643 = 82304
Step 129: 82304 + 643 = 82947
Step 130: 82947 + 643 = 83590
Step 131: 83590 + 643 = 84233
Step 132: 84233 + 643 = 84876
Step 133: 84876 + 643 = 85519
Step 134: 85519 + 643 = 86162
Step 135: 86162 + 643 = 86805
Step 136: 86805 + 643 = 87448
Step 137: 87448 + 643 = 88091
Step 138: 88091 + 643 = 88734
Step 139: 88734 + 643 = 89377
Step 140: 89377 + 643 = 90020
Step 141: 90020 + 643 = 90663
Step 142: 90663 + 643 = 91306
Step 143: 91306 + 643 = 91949
Step 144: 91949 + 643 = 92592
Step 145: 92592 + 643 = 93235
Step 146: 93235 + 643 = 93878
Step 147: 93878 + 643 = 94521
Step 148: 94521 + 643 = 95164
Step 149: 95164 + 643 = 95807
Step 150: 95807 + 643 = 96450
Step 151: 96450 + 643 = 97093
Step 152: 97093 + 643 = 97736
Step 153: 97736 + 643 = 98379
Step 154: 98379 + 643 = 99022
Step 155: 99022 + 643 = 99665
Step 156: 99665 + 643 = 100308
Step 157: 100308 + 643 = 100951
Step 158: 100951 + 643 = 101594
Step 159: 101594 + 643 = 102237
Step 160: 102237 + 643 = 102880
Step 161: 102880 + 643 = 103523
Step 162: 103523 + 643 = 104166
Step 163: 104166 + 643 = 104809
Step 164: 104809 + 643 = 105452
Step 165: 105452 + 643 = 106095
Step 166: 106095 + 643 = 106738
Step 167: 106738 + 643 = 107381
Step 168: 107381 + 643 = 108024
Step 169: 108024 + 643 = 108667
Step 170: 108667 + 643 = 109310
Step 171: 109310 + 643 = 109953
Step 172: 109953 + 643 = 110596
Step 173: 110596 + 643 = 111239
Step 174: 111239 + 643 = 111882
Step 175: 111882 + 643 = 112525
Step 176: 112525 + 643 = 113168
Step 177: 113168 + 643 = 113811
Step 178: 113811 + 643 = 114454
Step 179: 114454 + 643 = 115097
Step 180: 115097 + 643 = 115740
Step 181: 115740 + 643 = 116383
Step 182: 116383 + 643 = 117026
Step 183: 117026 + 643 = 117669
Step 184: 117669 + 643 = 118312
Step 185: 118312 + 643 = 118955
Step 186: 118955 + 643 = 119598
Step 187: 119598 + 643 = 120241
Step 188: 120241 + 643 = 120884
Step 189: 120884 + 643 = 121527
Step 190: 121527 + 643 = 122170
Step 191: 122170 + 643 = 122813
Step 192: 122813 + 643 = 123456
Step 193: 123456 + 643 = 124099
Step 194: 124099 + 643 = 124742
Step 195: 124742 + 643 = 125385
Step 196: 125385 + 643 = 126028
Step 197: 126028 + 643 = 126671
Step 198: 126671 + 643 = 127314
Step 199: 127314 + 643 = 127957
Step 200: 127957 + 643 = 128600
Step 201: 128600 + 643 = 129243
Step 202: 129243 + 643 = 129886
Step 203: 129886 + 643 = 130529
Step 204: 130529 + 643 = 131172
Step 205: 131172 + 643 = 131815
Step 206: 131815 + 643 = 132458
Step 207: 132458 + 643 = 133101
Step 208: 133101 + 643 = 133744
Step 209: 133744 + 643 = 134387
Step 210: 134387 + 643 = 135030
Step 211: 135030 + 643 = 135673
Step 212: 135673 + 643 = 136316
Step 213: 136316 + 643 = 136959
Step 214: 136959 + 643 = 137602
Step 215: 137602 + 643 = 138245
Step 216: 138245 + 643 = 138888
Step 217: 138888 + 643 = 139531
Step 218: 139531 + 643 = 140174
Step 219: 140174 + 643 = 140817
Step 220: 140817 + 643 = 141460
Step 221: 141460 + 643 = 142103
Step 222: 142103 + 643 = 142746
Step 223: 142746 + 643 = 143389
Step 224: 143389 + 643 = 144032
Step 225: 144032 + 643 = 144675
Step 226: 144675 + 643 = 145318
Step 227: 145318 + 643 = 145961
Step 228: 145961 + 643 = 146604
Step 229: 146604 + 643 = 147247
Step 230: 147247 + 643 = 147890
Step 231: 147890 + 643 = 148533
Step 232: 148533 + 643 = 149176
Step 233: 149176 + 643 = 149819
Step 234: 149819 + 643 = 150462
Step 235: 150462 + 643 = 151105
Step 236: 151105 + 643 = 151748
Step 237: 151748 + 643 = 152391
Step 238: 152391 + 643 = 153034
Step 239: 153034 + 643 = 153677
Step 240: 153677 + 643 = 154320
Step 241: 154320 + 643 = 154963
Step 242: 154963 + 643 = 155606
Step 243: 155606 + 643 = 156249
Step 244: 156249 + 643 = 156892
Step 245: 156892 + 643 = 157535
Step 246: 157535 + 643 = 158178
Step 247: 158178 + 643 = 158821
Step 248: 158821 + 643 = 159464
Step 249: 159464 + 643 = 160107
Step 250: 160107 + 643 = 160750
Step 251: 160750 + 643 = 161393
Step 252: 161393 + 643 = 162036
Step 253: 162036 + 643 = 162679
Step 254: 162679 + 643 = 163322
Step 255: 163322 + 643 = 163965
Step 256: 163965 + 643 = 164608
Step 257: 164608 + 643 = 165251
Step 258: 165251 + 643 = 165894
Step 259: 165894 + 643 = 166537
Step 260: 166537 + 643 = 167180
Step 261: 167180 + 643 = 167823
Step 262: 167823 + 643 = 168466
Step 263: 168466 + 643 = 169109
Step 264: 169109 + 643 = 169752
Step 265: 169752 + 643 = 170395
Step 266: 170395 + 643 = 171038
Step 267: 171038 + 643 = 171681
Step 268: 171681 + 643 = 172324
Step 269: 172324 + 643 = 172967
Step 270: 172967 + 643 = 173610
Step 271: 173610 + 643 = 174253
Step 272: 174253 + 643 = 174896
Step 273: 174896 + 643 = 175539
Step 274: 175539 + 643 = 176182
Step 275: 176182 + 643 = 176825
Step 276: 176825 + 643 = 177468
Step 277: 177468 + 643 = 178111
Step 278: 178111 + 643 = 178754
Step 279: 178754 + 643 = 179397
Step 280: 179397 + 643 = 180040
Step 281: 180040 + 643 = 180683
Step 282: 180683 + 643 = 181326
Step 283: 181326 + 643 = 181969
Step 284: 181969 + 643 = 182612
Step 285: 182612 + 643 = 183255
Step 286: 183255 + 643 = 183898
Step 287: 183898 + 643 = 184541
Step 288: 184541 + 643 = 185184
Step 289: 185184 + 643 = 185827
Step 290: 185827 + 643 = 186470
Step 291: 186470 + 643 = 187113
Step 292: 187113 + 643 = 187756
Step 293: 187756 + 643 = 188399
Step 294: 188399 + 643 = 189042
Step 295: 189042 + 643 = 189685
Step 296: 189685 + 643 = 190328
Step 297: 190328 + 643 = 190971
Step 298: 190971 + 643 = 191614
Step 299: 191614 + 643 = 192257
Step 300: 192257 + 643 = 192900
Step 301: 192900 + 643 = 193543
Step 302: 193543 + 643 = 194186
Step 303: 194186 + 643 = 194829
Step 304: 194829 + 643 = 195472
Step 305: 195472 + 643 = 196115
Step 306: 196115 + 643 = 196758
Step 307: 196758 + 643 = 197401
Step 308: 197401 + 643 = 198044
Step 309: 198044 + 643 = 198687
Step 310: 198687 + 643 = 199330
Step 311: 199330 + 643 = 199973
Step 312: 199973 + 643 = 200616
Step 313: 200616 + 643 = 201259
Step 314: 201259 + 643 = 201902
Step 315: 201902 + 643 = 202545
Step 316: 202545 + 643 = 203188
Step 317: 203188 + 643 = 203831
Step 318: 203831 + 643 = 204474
Step 319: 204474 + 643 = 205117
Step 320: 205117 + 643 = 205760
Step 321: 205760 + 643 = 206403
Step 322: 206403 + 643 = 207046
Step 323: 207046 + 643 = 207689
Step 324: 207689 + 643 = 208332
Step 325: 208332 + 643 = 208975
Step 326: 208975 + 643 = 209618
Step 327: 209618 + 643 = 210261
Step 328: 210261 + 643 = 210904
Step 329: 210904 + 643 = 211547
Step 330: 211547 + 643 = 212190
Step 331: 212190 + 643 = 212833
Step 332: 212833 + 643 = 213476
Step 333: 213476 + 643 = 214119
Step 334: 214119 + 643 = 214762
Step 335: 214762 + 643 = 215405
Step 336: 215405 + 643 = 216048
Step 337: 216048 + 643 = 216691
Step 338: 216691 + 643 = 217334
Step 339: 217334 + 643 = 217977
Step 340: 217977 + 643 = 218620
Step 341: 218620 + 643 = 219263
Step 342: 219263 + 643 = 219906
Step 343: 219906 + 643 = 220549
Step 344: 220549 + 643 = 221192
Step 345: 221192 + 643 = 221835
Step 346: 221835 + 643 = 222478
Step 347: 222478 + 643 = 223121
Step 348: 223121 + 643 = 223764
Step 349: 223764 + 643 = 224407
Step 350: 224407 + 643 = 225050
Step 351: 225050 + 643 = 225693
Step 352: 225693 + 643 = 226336
Step 353: 226336 + 643 = 226979
Step 354: 226979 + 643 = 227622
Step 355: 227622 + 643 = 228265
Step 356: 228265 + 643 = 228908
Step 357: 228908 + 643 = 229551
Step 358: 229551 + 643 = 230194
Step 359: 230194 + 643 = 230837
Step 360: 230837 + 643 = 231480
Step 361: 231480 + 643 = 232123
Step 362: 232123 + 643 = 232766
Step 363: 232766 + 643 = 233409
Step 364: 233409 + 643 = 234052
Step 365: 234052 + 643 = 234695
Step 366: 234695 + 643 = 235338
Step 367: 235338 + 643 = 235981
Step 368: 235981 + 643 = 236624
Step 369: 236624 + 643 = 237267
Step 370: 237267 + 643 = 237910
Step 371: 237910 + 643 = 238553
Step 372: 238553 + 643 = 239196
Step 373: 239196 + 643 = 239839
Step 374: 239839 + 643 = 240482
Step 375: 240482 + 643 = 241125
Step 376: 241125 + 643 = 241768
Step 377: 241768 + 643 = 242411
Step 378: 242411 + 643 = 243054
Step 379: 243054 + 643 = 243697
Step 380: 243697 + 643 = 244340
Step 381: 244340 + 643 = 244983
Step 382: 244983 + 643 = 245626
Step 383: 245626 + 643 = 246269
Step 384: 246269 + 643 = 246912
Step 385: 246912 + 643 = 247555
Step 386: 247555 + 643 = 248198
Step 387: 248198 + 643 = 248841
Step 388: 248841 + 643 = 249484
Step 389: 249484 + 643 = 250127
Step 390: 250127 + 643 = 250770
Step 391: 250770 + 643 = 251413
Step 392: 251413 + 643 = 252056
Step 393: 252056 + 643 = 252699
Step 394: 252699 + 643 = 253342
Step 395: 253342 + 643 = 253985
Step 396: 253985 + 643 = 254628
Step 397: 254628 + 643 = 255271
Step 398: 255271 + 643 = 255914
Step 399: 255914 + 643 = 256557
Step 400: 256557 + 643 = 257200
Step 401: 257200 + 643 = 257843
Step 402: 257843 + 643 = 258486
Step 403: 258486 + 643 = 259129
Step 404: 259129 + 643 = 259772
Step 405: 259772 + 643 = 260415
Step 406: 260415 + 643 = 261058
Step 407: 261058 + 643 = 261701
Step 408: 261701 + 643 = 262344
Step 409: 262344 + 643 = 262987
Step 410: 262987 + 643 = 263630
Step 411: 263630 + 643 = 264273
Step 412: 264273 + 643 = 264916
Step 413: 264916 + 643 = 265559
Step 414: 265559 + 643 = 266202
Step 415: 266202 + 643 = 266845
Step 416: 266845 + 643 = 267488
Step 417: 267488 + 643 = 268131
Step 418: 268131 + 643 = 268774
Step 419: 268774 + 643 = 269417
Step 420: 269417 + 643 = 270060
Step 421: 270060 + 643 = 270703
Step 422: 270703 + 643 = 271346
Step 423: 271346 + 643 = 271989
Step 424: 271989 + 643 = 272632
Step 425: 272632 + 643 = 273275

So, 643*425 = 273275